20904578 has 18 divisors (see below), whose sum is σ = 32492187. Its totient is φ = 10086960.

The previous prime is 20904511. The next prime is 20904589. The reversal of 20904578 is 87540902.

It is a happy number.

It can be written as a sum of positive squares in 5 ways, for example, as 3323329 + 17581249 = 1823^2 + 4193^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3233.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 342668 + ... + 342728.

Almost surely, 2^20904578 is an apocalyptic number.

20904578 is a deficient number, since it is larger than the sum of its proper divisors (11587609).

20904578 is an frugal number, since it uses more digits than its factorization.

20904578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20904578 is about 4572.1524471522. The cubic root of 20904578 is about 275.4739068154.

The spelling of 20904578 in words is "twenty million, nine hundred four thousand, five hundred seventy-eight".